Family

DNA gyrase, subunit A (IPR005743)

Short name: GyrA

Overlapping homologous superfamilies

Family relationships

None.

Description

DNA topoisomerases regulate the number of topological links between two DNA strands (i.e. change the number of superhelical turns) by catalysing transient single- or double-strand breaks, crossing the strands through one another, then resealing the breaks [PMID: 7770916]. These enzymes have several functions: to remove DNA supercoils during transcription and DNA replication; for strand breakage during recombination; for chromosome condensation; and to disentangle intertwined DNA during mitosis [PMID: 12042765, PMID: 11395412]. DNA topoisomerases are divided into two classes: type I enzymes (EC:5.99.1.2; topoisomerases I, III and V) break single-strand DNA, and type II enzymes (EC:5.99.1.3; topoisomerases II, IV and VI) break double-strand DNA [PMID: 12596227].

Type II topoisomerases are ATP-dependent enzymes, and can be subdivided according to their structure and reaction mechanisms: type IIA (topoisomerase II or gyrase, and topoisomerase IV) and type IIB (topoisomerase VI). These enzymes are responsible for relaxing supercoiled DNA as well as for introducing both negative and positive supercoils [PMID: 7980433].

Topoisomerase II (called gyrase in bacteria) primarily introduces negative supercoils into DNA. In bacteria, topoisomerase II consists of two polypeptide subunits, gyrA and gyrB, which form a heterotetramer: (BA)2. In most eukaryotes, topoisomerase II consists of a single polypeptide, where the N- and C-terminal regions correspond to gyrB and gyrA, respectively.

This entry represents the A subunit (gyrA) as found predominantly in bacteria, but does not include the topoisomerase II enzymes composed of a single polypeptide, as are found in most eukaryotes. GyrA has two functional domains: an N-terminal that forms the covalent DNA-protein bridge that is responsible for the breaking- and rejoining function, and a C-terminal that can bind DNA non-specifically [PMID: 8982450].

GO terms

Biological Process

GO:0006265 DNA topological change

Molecular Function

GO:0005524 ATP binding
GO:0003677 DNA binding
GO:0003918 DNA topoisomerase type II (ATP-hydrolyzing) activity

Cellular Component

GO:0005694 chromosome

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.
HAMAP